preprints.org > environmental and earth sciences > atmospheric science and meteorology > doi: 10.20944/preprints202411.0184.v1

Preprint Article Version 1 This version is not peer-reviewed

Version 1 : Received: 4 November 2024 / Approved: 4 November 2024 / Online: 4 November 2024 (12:20:47 CET)

Atmospheric pollution caused by aerosols deteriorate air quality, increasing public health risk. Anthropogenic aerosols are mostly concentrated within the atmospheric boundary layer (ABL), that presents a daytime evolution that determine the vertical mixing of the air pollutants generated near the surface and therefore, their ground-level concentration from local sources. Proper characterization of this layer is of crucial importance in numerical weather forecasting and climate models; however, their estimation nowadays presents some spatial and temporal limitations. Lidars have demonstrated their capabilities to study the aerosol vertical distribution. A particular type of lidars, ceilometers, are capable of providing continuous aerosol vertical profiles with good spatial resolution and a large vertical range. Advanced methods, such as the recently developed STRATfinder algorithm, are required to estimate the ABL height due to difficulties with residual layers. The algorithm tracks ABL heights to provide values every hour during a 24-hour period. More complex situations occur due to advection of aerosols (e.g. due to long-range transport of desert dust, volcanic eruptions, or pyrocloud convection), producing lofted layer in the free troposphere that may remain decoupled from the local ABL but can also be mixed. Aerosol-based methods for determination of the ABL height are challenging in those situations. The main objective of this research is the assessment of the impact of Saharan dust intrusions on the ABL using ceilometer signals, along four years period 2020-2023. The database of ABL heights of continuous measurements have been classified regarding the most frequent patterns of synoptic circulation. Six synoptic meteorological patterns were identified through cluster analysis of sea level pressure fields as the main responsible of the weather conditions in the Iberian Peninsula. Counter-intuitive behavior is obtained in particular synoptic situations due to the presence of dust-rich aloft layers. These results are relevant for health advice during Saharan dust intrusion days.

atmospheric boundary layer; ceilometer; aerosols; Saharan dust; atmospheric pollution

Environmental and Earth Sciences, Atmospheric Science and Meteorology

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